IG1 21.05 smc
Detection of microsatellite variation by capillary gel electrophoresis

    Microsatellite variation is detected by a combination of PCR amplification and electrophoretic separation. Once a microsatellite locus is identified, two PCR priming sites with unique DNA sequences are identified on either side of the repeat region [top]. PCR amplification generates a DNA fragment of a particular size [middle], depending on the number of repeats in the microsatellite locus present. The size of the allele can be measured by the use of DNA size markers run simultaneously with the PCR product by capillary electrophoresis [bottom].

In the example, the individual is heterozygous for two alleles that are both amplified by the same PCR primers and are detected as two fragments of 184bp and 188bp.

Figure ©2012 TA Brown, Introduction to Genetics (1st ed.); additional text ©2013 by Steven M. Carr